The Dolphins have installed about 70 percent of the game plan for Sunday's home game against Buffalo but starting middle linebacker Dannell Ellerbe has had to sit out this week's practices.

Ellerbe sat out his second straight practice because of a shoulder injury he suffered in the Oct. 6 loss to the Ravens. The team's leading tackler worked with Dolphins trainers while his teammates practiced.

Jason Trusnik replaced Ellerbe as the inside linebacker paired with Koa Misi and Philip Wheeler. Trusnik has played in the Dolphins base defense the past four games because of injuries to Miami's linebackers and he's contributed six tackles.

On Monday Ellerbe said he was confident he'll play after spending all of his bye week rehabbing with trainers. But he has two more practices before the Dolphins wrap up the week of preparation for the Bills (2-4) which features a dynamic tailback tandem of C.J. Spiller and Fred Jackson and an athletic quarterback in Thad Lewis.

The Bills are averaging 4.3 yards per carry and have scored five rushing touchdowns this season. In this defense the middle linebacker's primary responsibility is to contain the run and cover tailbacks down-field.